Photographic sensitizer material



W. ZEH

PHOTOGRAPHIC SENSITIZER MATERIAL Filed Feb. 5, 1952 Aug, l0, w37.

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Patented Aug. 10, 1937 UNITED STATES PATENT OFFICE 2,089,321 PHOTOGRAPHIC SENSITIZER, MATERIAL Application February 3, 1932, Serial No. 590,772 In Germany February 3, 1931 6 Claims.

I have found that a silver-halide emulsion especially a silver-chloride emulsion containing a benzoselenazolemethine-cyanine of the general formula Formula 1:

N l r N PX V=H, alkyl, alkoxy, benzene, halide,

r=alkyl, X=halide, perchlorate, para-toluene, sulfonate, alkvlo-sulfate, nitrate,

shows an increased sensitiveness within the blue region of the spectrum. The range of sensitiveness of an emulsion comprising a short region of individual sensitiveness will be increased, or if the region of'individual sensitiveness will not be in- 40 creased by addition of the sensitizer its sensitiveness within the region of individual sensibility may be increased. The sensitizers are therefore well suited for sensitizing silver-chloride emulr sions which may be used in color photography. 4" In general Formula-1 V may be linked to any position in the benzene nuclei, however, the 5 and 6 position and the 5' and 6' position are preferred. V may be an alkyl, such as methyl, ethyl, etc. or an alkoxyA group, for instance, a

methoxy or an ethoxy group, or halide, or benzene. r may be alkyl, for example methyl or ethyl. X can be any suitable anion, for instance, a halide, paratoluene sulfonate, alkylosulfate, perchloratenitrate, or the like.

In the accompanying graph there are reproduced 3 spectrograms of the same silver-halide gelatin emulsion.

Fig. 1 shows the spectrogram of an unsensitized silver-chloride emulsion,

Fig. 2 that of a silver-chloride emulsion containing bis- [S-ethyl-benzoselefnazole- (2) l-methinecyanineiodide, and

Fig. 3 illustrates the spectrogram of silverchloride emulsion containing bis [3 ethyl 5 10 ethoxy-benzoselenazole (2)] methinecyanlneiodide.

In these spectrograms the abscisvsae are graduated in milllmicrons (ya) while the ordinates are graduated in divisions denoting the blackenl5 lng of the tested film. The blackenings are taken by exposing the film in a diffraction grating spectrograph of Carl Zeiss, Jena, provided with a Rowland diffraction grating, and illuminating with a nitra lamp of A watts through 20 a stage slot.

When comparing the curves the influence of the sensitizers on the sensitiveness of the emulsion may be easily seen. The spectrograms oi. the emulsion containing a sensitizing material is 25 distinguished from the spectrogram of the unsensitized emulsion by its characteristic form.

The dyes are obtainable according to the desired solubility in form of the bromide, iodide, perchlorate, etc. and are used in a quantity as 30 usual for the known sensitizing dyes. This quantity amounts to about 15 to 30 milligrams per 1 kg. of emulsion ready for being cast which contains about 9 per cent of gelatin, 4.5 per cent of silver-halide, the rest being water. However I 35 do not wish to limit my invention to the quantities just indicated, the most suitable amount will in each casebe found by a. few comparative experiments. The dyes may be added to the emulsion in form of solutions. Suitable solvents 40 are the alcohols, for instance, methyl or ethyl alcohol which may be used anhydrous or diluted with water. 'I'he dyes may be applied to the emulsion during any stage of lts production, however, they are preferably added to the finished 45 emulsion before being cast. The dyes may likewise be added by coating the emulsion with them or by bathing the finished photographic material in a bath in which the dye is dissolved. The dyes are suited for sensitizing an emulsion 'made ac- 50 cording to the boiling process as well as for sensitizing an emulsion made accordingto the am- 11101118. DIOCESS.

The following examples serve to illustrate my invention. 55

Example 1.-For producing the dye bis-[3- I iodide corrponding to the formula '1- grams of Z-methyl-benzselenazole-ethyl-iodide are heated with 50 cc. of acetic anhydride until boiling and then there are added 3 cc. of amyl nitrite. While vehemently frcthing' the dye separates from the brownish yellow colored solution inform of greenish yellow ilelres. By recrystallisation from alcohol the dye is obtainable as green shining needles. K

The alcoholic solution of the dye shows an absorption maximum at awave length of about Incorporated in a gelatina-silver-chloride emulsion the dye imparts toit a range of sensitiveness from about 430ML to about 500W. with a mainmum at about 460m.

.Example 2.For producing the dye bia-[3- ethyl--ethoxy-benzoselenazole (2)] methinecyanine-iodide corresponding to the formino there ere added 1.5 ce. of ethyl nitrite te e honing solution of 4 grams of 2-methyl-5-ethoxy-benzselenazole-ethyl-iodide irr 30 cc. of acetic anhydride. While vehemently frothing the dye separates from the solution in form of yellow flakes. The dye is obtainable in form of yellow felted 'needles by recrystallization from alcohol.

The alcoholic solution of the dye shows an absorption maximum at a wave length Yof about 440ML.

i Incorporated in a gelatino-silver-chloride emulsion the dye imparts to it a range oi' sensitivefness from about 430W to about 520ml with a maximum at about 479ml.

Example 3.-The ,dye bis-[3-ethyl-5-chloro- I benzoselenazole- (2) l-methinecyanine-iodide corresponding to 'the formula in e is precipitated from the ,boiling solution of 4 grams of 2-methyl-5-chloro-ben2selenazole-ethyl-iodide in 30 cc. of acetic anhydride by addition of 2 cc. of amyl nitrite in form of greenish yellow flakes. Recrystallization ofthe dye from alcoho yields ne needles.

- The alcoholic solution of the dye shows an absorption 'maximum at a wave length of about 425ML.

Incorporated in a'gelatino-silver-chloride emulrsion the dye imparts to it a range of sensitiveness from about 430m to about 510ml. with a maximum at about 472W.

sample 4.-'rne dye bis-[a-ethyi-'e-metnoxybenzoselenazole-(Z) l-methinecyanine-iodide corresponding to the formula moo om l H i 3 grams of 2-methyl-a-naphthol-selenafzole-ethyl-bromide are heated with 10 cc. of acetic anhydride until boiling. The dye separates on addition of 1 cc. of amyl-nitrite from. the brownish yellowl colored liquid in form of'sma'll crystal druses. 'I'he ltered product is washed with acetone and ether and recrystallized from methanol. y Y.

'I'he alcoholic solution of the dye shows an absorption maximum at a wave length of about Incorporated in a gelatino-silver-chloride emul-f sion the dye imparts to it a range of sensitiveness from about 430ML to about 530ml with a maximum at about 485ml.

The bases serving as a starting material for the production of the dyes are obtainableaccording to methods known from the preparation oi' the unsubstituted benzselenazoles.

It is to be understood that my invention is not limited to the foregoing examples nor to the speciilc details given therein. Numerous other embodiments are possible and I contemplate as included within my invention all such modincations and equivalents as fall within the scopeof the appendedclaims. So. for instance, the benzene nuclei may contain one or more substituents. The nomenclature used is arbitrary,

4but it is familiar to every chemist skilled in theart and has the advantage of clearness. N'umbering of the .basis is commenced from the selenium atom and of the'dyes from the nitrogen atom. The formulae ofthe dyes as given herein represent the molecular structure of my new dyes so far as known. If, however, in future it should become evident that the formulae do not exactly correspond tothe dyes this fact will not aifect my invention since the dyes will ,be easily identified by the method'of producing the same which has been fully described in the example and is analogous to known methods.

What I claim is:

1. A photographic material comprising a silver-halide emulsion containing bis-[B-ethyl-- ethoxy benzselenazo1e`(2) l-methinecyanine-iodide corresponding probably to the formula 7 6 1 H l1 5 zij-o 2' me, 4 3 005m gl (IlsHs 2. A photographic material comprising a silver-halide emulsion containing bis- [Ii-ethyl-G- methoxy benzselenazole (2) methinecyanineiodide corresponding probably to the formula Hzo\ 7 e /ocm g1 alla 3. A photographic material comprising a silver-halide emulsion containing bis- [i3-methylnaphthol1'.2' :4.5-selenazole- (2) -l methinecyanine-bromide, corresponding probably to the formula.

4. A photographic material comprising a silver halide emulsion containing a benzoselenazolemethine-cyanine salt.

5. A photographic material comprising a sil-l 

